If 4/5 x blank = 2/5, what is blank

1/2

Step-by-step explanation:

Better write, "If (4/5)x = 2/5, what is x?  Please do not use 'x' to denote multiplication; use " * " instead.

If (4/5)x = 2/5, multiplying both sides by (5/4) will isolate x:

(5/4)(4/5)x = (5/4)(2/5), or

               x = 10/20, or x = 1/2.  The unknown number is 1/2.

step-by-step explanation:

there would only be 50 odd numbers between 1 and 100 so therefor there would be 50 even so that would only be 50 odd numbers.